This relates generally to computer processing and, particularly, to graphics processing.
In graphics processing, pixels in screen space must be projected or mapped into texture space in order to be textured. A 2×2 stamp or quad of pixels is projected from the x,y screen space to the u,v texture space. The projection of the original pixels results in four sample points within the texture space. The four texels around each sample point are then filtered to return four filtered colors, one per sample.
If the projections land near each other, all of the texels between the projections contribute to the final color, yielding a projection that avoids aliasing artifacts. If the projections land too far away from one another, the texels between the sample points do not contribute to the final color. This results in low quality, due to aliasing. If the projections are similar distances from each other, this may be solved through mipmapping. If the projections are not at similar distances from each other then mipmapping to avoid aliasing results in low quality by introducing blurring. Anisotropic filtering must be used in this case to avoid both aliasing and blurring artifacts.
Anisotropic filtering enhances the image quality of texels on surfaces that are at oblique viewing angles, with respect to the camera, where the projection of the texture appears to be non-orthogonal. Anisotropic filtering may reduce or eliminate aliasing effects without introducing blurring.